1. Field of the Invention
The present invention relates to a computer peripheral unit which is compatible with a Universal Serial Bus (hereinafter referred to as USB) interface and particularly to a computer peripheral unit which requires more than the level of power which a USB interface can supply.
2. Description of Related Art
In recent years, there has been a tendency for USB interface-compatible computer peripheral units to be increasingly used. In addition to USB interface-compatible mice and keyboards, for example, some floppy disk drives are compatible with USB interfaces.
A conventional USB interface-compatible floppy disk drive is connected with a computer only via a USB cable. The USB cable includes power supply wires through which power is supplied to the floppy disk drive. The power supplied to the floppy disk drive in this way is up to 500 mA in accordance with the USB interface specification. The voltage is constant at 5V.
The abovementioned conventional floppy disk drive incorporates devices with relatively large power consumption, such as a spindle motor for rotating the disk and a stepping motor for moving the heads. Therefore, if the floppy disk drive is connected at an end of the power supply line on which a plurality of computer peripheral units are connected using a USB hub, the maximum power which can be supplied to it would be smaller than the abovementioned level or 500 mA, leading to a problem that the floppy drive does not work.
When a USB interface is used, a data transfer rate can be higher than in the conventional floppy disk drive. However, in order to increase the data transfer rate, the rotating speed of the disk must be increased. However, because the maximum power available to it is 500 mA in accordance with the USB interface specification as mentioned above, it is impossible to supply sufficient power to increase the rotating speed.
To solve the above problem, the present invention provides a computer peripheral unit which can supply sufficient power to improve performance and increase a processing speed, not subject to the power supply limitation by a USB interface specification.
The present invention provides a computer peripheral unit which is connected with a main computer unit through a Universal Serial Bus interface, the peripheral unit comprising: a first input section which receives bus power fed through a bus on the Universal Serial Bus interface; a second input section which receives higher power than the abovementioned bus power; and a control section which determines whether the power being supplied is bus power from the first input section or power from the second input section.
Preferably, the peripheral unit has detecting means for detecting power supply from the second input section and a detection signal from which the detecting means is given to the control section to switch a power supply route to a route for the second input section.
According to the present invention, when power is supplied from the second input section, it can be recognized by the control section and finally the performance of the connected peripheral unit can be improved. When two or more peripheral units are connected, even if a peripheral unit with large power consumption is connected at the end of the power supply line, power can be supplied from the second input section according to the decision by the control section, thereby preventing the unit from failing to operate.
For example, the peripheral unit may be a disk drive which can house a disk and perform recording and/or reproduction while the disk is rotating, wherein the disk is rotated at a higher speed than a regular rotating speed when power is supplied from the second input section.
With the abovementioned constitution, the rate of data transfer between the computer and peripheral unit can be increased, thereby reducing the processing time.